Question

MongoDB CRUD Operations Step by Step Guide

Answer 1

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*MongoDB CRUD Operations Step by Step Guide*

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YouTube Video link:

MongoDB Database server:

Server IP: 192.168.224.xxx

MongoDB provides CRUD (Create, Read, Update, Delete) operations to manage data. Below are detailed steps with examples for each operation.

Access MongoDB Datababase in command line:

mongosh --host 127.0.0.1 --port 27017 -u "admin" -p "admin@123" --authenticationDatabase "admin"

--or--

mongosh --host 127.0.0.1 --port 27017 -u "admin" -p "admin@123"

Grant Appropriate Role: If the user does not have sufficient permissions, you'll need to grant them the necessary role. For example, to grant the readWrite role on the "chirags" database, use the following command:

db.updateUser("admin", { roles: [{ role: "readWrite", db: "chirags" }] })

1. Create (Insert)

Used to add new documents to a MongoDB collection.

Example: Insert a single document

First select database:

test> use chirags

switched to db chirags

chirags>

Now Insert data into chirags database:

chirags> db.users.insertOne({
  name: "Chirag Mahto",
  age: 30,
  city: "Ranchi"
})

Example: Insert multiple documents

chirags> db.users.insertMany([
  { name: "Purab", age: 35, city: "Ranchi" },
  { name: "Sanju", age: 30, city: "Jamshedpur" }
])

Explanation:

insertOne() is used for inserting a single document.

insertMany() allows insertion of multiple documents in an array.

2. Read (Query)

Used to fetch data from a collection.

Example: Find all documents

chirags> db.users.find()

Example: Find documents with specific criteria

chirags> db.users.find({ age: { $gt: 30 } })

Example: Find only one document

chirags> db.users.findOne({ name: "Purab" })

Explanation:

find() retrieves all matching documents. You can add filters like { age: { $gt: 35 } } to query based on conditions (e.g., age greater than 35).

findOne() returns the first matching document.

Advanced Query Example: Query with Projection

chirags> db.users.find({ age: { $gt: 33 } }, { name: 1, city: 1, _id: 0 })

Explanation: The second argument specifies the fields to return. { name: 1, city: 1, _id: 0 } shows only name and city while excluding _id.

3. Update

Used to modify existing documents in a collection.

Example: Update a single document

chirags> db.users.updateOne(
  { name: "Chirag Mahto" },  // filter
  { $set: { age: 33 } }  // update operation
)

Example: Update multiple documents

chirags> db.users.updateMany(
  { city: "Ranchi" },   // filter
  { $set: { city: "Bokaro" } }  // update operation
)

Example: Replace a document

chirags> db.users.replaceOne(
  { name: "Chirag Mahto" },  // filter
  { name: "Chirag", age: 36, city: "Dhanbad" }  // new document
)

Explanation:

updateOne() updates the first document that matches the filter.

updateMany() updates all documents that match the filter.

replaceOne() replaces an entire document with a new one.

Example: Update with Operators

chirags> db.users.updateOne(
  { name: "Chirag" },
  { $inc: { age: 1 }, $set: { city: "myCity" } }
)

Explanation: $inc increments the age field by 1, and $set updates the city field.

4. Delete

Used to remove documents from a collection.

Example: Delete a single document

chirags> db.users.deleteOne({ name: "Chirag" })

Example: Delete multiple documents

chirags> db.users.deleteMany({ age: { $lt: 30 } })

Explanation:

deleteOne() deletes the first matching document.

deleteMany() deletes all documents that match the filter.

Summary of Common MongoDB Operators

$gt, $lt, $gte, $lte: Greater than, Less than, Greater than or equal to, Less than or equal to.

$set: Set a value for a field.

$inc: Increment a field's value.

$and, $or: Logical AND, OR operations for multiple conditions.

For any doubts and query, please write on YouTube video comments section.

Note : Flow the Process shown in video.

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Thanks & Regards,

Chitt Ranjan Mahto "Chirag"

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